Battery monitoring apparatus with monitoring integrated circuit selectively powered by a high voltage battery or low voltage power supply powered by a low voltage battery

ABSTRACT

A battery monitoring apparatus capable of reducing power consumption. At least one monitoring integrated circuit (IC) is electrically connected to a high-voltage battery formed of a plurality of cells and configured to monitor the high-voltage battery in a plurality of modes of operation. A low-voltage power supply circuit can deliver power of a lower voltage than the power of the high-voltage battery to the at least one monitoring IC. A power supply to the at least one monitoring IC is selected from a group of the high-voltage battery and the low-voltage power supply circuit depending on the mode of operation the at least one monitoring IC.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority fromearlier Japanese Patent Application No. 2013-214733 filed Oct. 15, 2013,the description of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present invention relates to a battery monitoring apparatusincluding monitoring integrated circuits (ICs) for monitoring ahigh-voltage battery formed of a plurality of cells.

Related Art

A known battery monitoring apparatus, as disclosed in Japanese PatentApplication Laid-Open Publication No. 2003-70179, includes monitoringICs for monitoring and adjusting the capacity of each of a plurality ofcells forming a high-voltage battery, where the monitoring ICs aresupplied with power from the high-voltage battery.

The apparatus disclosed in Japanese Patent Application Laid-OpenPublication No. 2003-70179 is configured such that the monitoring ICsare always supplied with power from the high-voltage battery, whichleads to increased power consumption for the high-voltage battery todrive the cells. The power consumption varies with the monitoring ICs ofthe high-voltage battery, which will cause variations in capacity withthe cells. Control with use of the high-voltage battery is tailored toone of the cells having a minimum capacity, which may prevent thehigh-voltage battery from delivering its inherent performance in thepresence of variations in capacity with the cells.

In consideration of the foregoing, it would therefore be desirable tohave a battery monitoring apparatus capable of reducing the high-voltagebattery power consumption of monitoring ICs of the apparatus.

SUMMARY

In accordance with an exemplary embodiment of the present invention,there is provided a battery monitoring apparatus including: at least onemonitoring integrated circuit (IC) that is electrically connected to ahigh-voltage battery formed of a plurality of cells and configured tomonitor the high-voltage battery in a plurality of modes of operation;and a low-voltage power supply circuit that can deliver power of a lowervoltage than the power of the high-voltage battery to the at least onemonitoring IC. In the apparatus, a power supply to the at least onemonitoring IC is selected from a group of the high-voltage battery andthe low-voltage power supply circuit depending on the mode of operationof the at least one monitoring IC.

With this configuration, a power supply used to supply power to themonitoring ICs can be selected depending on modes of operation of themonitoring ICs, which can reduce power supplied from the high-voltagebattery to the monitoring ICs. This can reduce variations in thecapacity of each of the cells of the high-voltage battery caused bypower supply to the monitoring ICs and allow the high-voltage battery todeliver its inherent performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit block diagram illustrating the overallconfiguration of a battery monitoring apparatus in accordance with oneembodiment of the present invention;

FIG. 2 is a schematic circuit block diagram of one of monitoring ICswithin the battery monitoring apparatus of FIG. 1;

FIG. 3A is a schematic illustrating second-class modes of operation ofone of monitoring ICs within the battery monitoring apparatus of FIG. 1;and

FIG. 3B is a schematic illustrating first-class modes of operation ofone of monitoring ICs within the battery monitoring apparatus of FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings. A battery monitoring apparatusin accordance with one embodiment of the present invention may bemounted in a hybrid (HV) vehicle including a lithium ion battery, whichis a high-voltage battery formed of a plurality of cells, and a leadbattery, which is a low-voltage battery, and is configured to monitorcapacities of the respective cells of the lithium ion battery.

FIG. 1 is a circuit block diagram of a battery monitoring apparatus ofthe present embodiment.

The battery monitoring apparatus 100 includes a plurality of monitoringICs 110, and an insulating power supply block 120, which is alow-voltage power supply circuit, configured to supply power to theplurality of monitoring ICs 110. The battery monitoring apparatus 100 isconfigured to receive control signals from a higher-level ECU (notshown).

The insulating power supply block 120 includes a power supply integratedcircuit (IC) 121 and a centralized transformer 122. The centralizedtransformer 122 is formed of a single primary coil 122 a and a pluralityof secondary coils 122 b. Passing a current through the primary coil 122a simultaneously induces currents flowing through the plurality ofsecondary coils 122 b, which enables parallel power supply to theplurality of monitoring ICs 110. The centralized transformer 122 canalso serve as an insulator. A current produced in each of the secondarycoils 122 b is delivered to corresponding one of the monitoring ICs 110through a rectification circuit formed of a diode 123 and a capacitor124. The power supply IC 121 is configured to control the centralizedtransformer 122 on the basis of the control signals received from thehigher-level ECU to regulate power to be delivered to the plurality ofmonitoring ICs 110.

The battery monitoring apparatus 100 is electrically connected to thehigh-voltage battery 200 formed of a plurality of cells 201 and to thelow-voltage battery 300, thereby enabling power supply from either orboth of them. The high-voltage battery 200 and the low-voltage battery300 may be charged by chargers (not shown), for example, by ahigh-voltage battery charger and a low-voltage battery charger,respectively. The monitoring ICs 110 are configured to acquire voltagesof the plurality of cells 201 of the high-voltage battery 200 andcontrol the cells in response to the acquired voltages of them. In thepresent embodiment, each monitoring IC 110 may be responsible forcontrolling some of the plurality of cells of the high-voltage battery200, that is, a predetermined number of cells which are subject tocontrol of the monitoring IC 110.

The low-voltage battery 300 is electrically connected to the insulatingpower supply block 120 through a transistor 130 that is an externalswitching element. Switching of the transistor 130 between open andclosed states is controlled in response to the control signals from thehigher-level ECU.

FIG. 2 is a schematic circuit block diagram for each of the monitoringICs of the battery monitoring apparatus 100. Since the monitoring ICsare similar in configuration to each other, one of the monitoring ICswill now be explained. The explanation for the other monitoring ICs willnot be repeated.

The monitoring IC 110 includes a first switch 111, a second switch 112,a first power supply circuit 113, a second power supply circuit 114, athird power supply circuit 115, a fourth power supply circuit 116, andan oscillation and logic circuit 117. The oscillation and logic circuit117 includes a high-voltage driven section and a low-voltage drivensection. The high-voltage driven section can be driven at a lowercurrent value as compared with the low-voltage driven section. Themonitoring IC 110 may include a memory (not shown).

Modes of operation for the monitoring IC 110 will now be explained.

Modes of operation for the monitoring IC 110 are classified intofirst-class modes of operation, in which the power consumption is equalto or greater than a predetermined value, and second-class modes ofoperation, in which the power consumption is less than the predeterminedvalue. The first- and second-class modes of operation are predefined andstored in a memory (not shown) within the higher-level ECU.

The first-class modes of operation include a self-diagnostic mode ofoperation and the like. In the self-diagnostic mode of operation, themonitoring IC 110 acquires, for each of the cells 201 associated withthe monitoring IC 110, a voltage across the cell 201, and calculates aninternal resistance and a capacity of the cell 201 on the basis of theacquired voltage of the cell 201. The monitoring IC 110 furthercalculates, for each of the cells 201 associated with the monitoring IC110, an amount of voltage drop for a predetermined time period todetermine a deteriorating condition of the cell 201. The calculatedinternal resistance and capacity and the determined deterioratingcondition for each of the cells 201 associated with the monitoring IC110 are to be stored in the memory of the monitoring IC 110.

The calculated internal resistance and capacity and the determineddeteriorating condition for each of the cells 201 associated with themonitoring IC 110 are to be transmitted to the higher-level ECU. Thehigher-level ECU controls the high-voltage battery charger on the basisof the calculated internal resistance and capacity and the determineddeteriorating condition received for each of the cells 201 associatedwith the monitoring IC 110. The monitoring IC 110 determines, for eachof the cells 201 associated with the monitoring IC 110, whether or notthe capacity of the cell 201 is less than a first predeterminedthreshold. When it is determined that the capacity of the cell 201 isless than the first predetermined threshold, the monitoring IC 110determines that the cell 201 is in an over-discharge condition andcharges the cell 201 by adjusting the voltage of the high-voltagebattery charger. When it is determined that the capacity of the cell 201is greater than a second threshold that is greater than the firstpredetermined threshold, the monitoring IC 110 determines that the cell201 is in an over-charge condition and discharges the cell 201 byadjusting the voltage of the high-voltage battery charger.

The second-class modes of operation include an equalization mode ofoperation and a sleep mode of operation and the like.

The monitoring IC 110 transitions into the equalization mode ofoperation at predetermined time intervals to perform an equalizingoperation. In the equalizing operation, the monitoring IC 110 acquires avoltage across each of the cells 201 associated with the monitoring IC110 and compares the voltages of the cells 201 associated with themonitoring IC 110 with each other. To equalize the capacity between thecells 201 associated with the monitoring IC 110, the monitoring IC 110discharges the cell 201 having a relatively high voltage via theoscillation and logic circuit 117, thereby reducing the capacity of therelatively high voltage cell 201. This equalizing operation is repeateduntil a difference in voltage between the highest voltage cell 201 andthe lowest voltage cell 201 becomes less than a predetermined value sothat the capacities of the cells 201 associated with the monitoring IC110 become almost equal to each other.

The monitoring IC 110 transitions into the sleep mode of operation whena vehicle-mounted ignition switch is turned off. In the sleep mode ofoperation, an idle mode of operation is performed where only a timer(not shown) and the memory included in control mean (for various controloperations) of the monitoring IC 110 are powered by the first powersupply circuit 113 and power to the other components included in thecontrol mean is cut. That is, none of various control functions areexecuted.

Upon transitions between the first-class modes of operation and thesecond-class modes of operation, the first switch 111 and the secondswitch 112 are controlled to select a power supply.

Open and closed states of the first and second switches 111, 112 in thefirst-class modes of operation will now be explained.

In the first-class modes of operation, the first switch 111 and thesecond switch 112 are both closed. A current input from the high-voltagebattery 200 is kept at a specified voltage by the first power supplycircuit 113 to be used for driving the high-voltage driven section ofthe oscillation and logic circuit 117.

A current input from the insulating power supply block 120 is steppeddown to a specified voltage by the second power supply circuit 114 to befed to the third power supply circuit 115 that is a digital power supplycircuit within the monitoring IC 110. The current output from the thirdpower supply circuit 115 is used for driving the low-voltage drivensection of the oscillation and logic circuit 117.

The fourth power supply circuit 116 is a power supply circuit fordriving a photocoupler (not shown). The fourth power supply circuit 116steps down the power input from the insulating power supply block 120 toa specified voltage for driving the photocoupler configured to receivesignals from and transmit signals to the higher-level ECU. In thefirst-class modes of operation, the photocoupler is used to transmitsignals indicative of the internal resistance, the capacity, and thedeteriorating condition of each of the cells 201, to the higher-levelECU.

There will now be explained how the switches are controlled upontransitions between the first-class modes of operation and thesecond-class modes of operation.

Upon transitions from the first-class modes of operation to thesecond-class modes of operation, a blocking signal for blocking thecurrent input from the insulating power supply block 120 is transmittedfrom the higher-level ECU to the battery monitoring apparatus 100 as themonitoring IC 110 doesn't need any current input from the insulatingpower supply block 120. Upon receipt of the blocking signal, as shown inFIG. 3A, the battery monitoring apparatus 100 keeps the first switch 111closed and opens the second switch 112. In addition, a terminationsignal is transmitted from the higher-level ECU to the batterymonitoring apparatus 100 for terminating the insulating power supplyblock 120 by turning off the transistor 130. Power from the low-voltagebattery 300 to the insulating power supply block 120 is thereby cut.

Upon transitions from the second-class modes of operation to thefirst-class modes of operation, as shown in FIG. 3B, the batterymonitoring apparatus 100 keeps the first switch 111 closed and closesthe second switch 112 and the transistor 130 in response to the controlsignal from the higher-level ECU. The closed state of the transistor 130allows the power supply IC 121 to be supplied with power and control ofthe insulating power supply block 120 is thereby initiated. Since thecentralized transformer 122 supplies power to the plurality ofmonitoring ICs 110 simultaneously, circuits within the respectivemonitoring ICs 110, powered by the insulating power supply block 120,will be activated simultaneously.

The battery monitoring apparatus 100 configured as above can provide thefollowing advantages.

As above, a power supply used to supply power to the monitoring ICs 110can be selected depending on modes of operation of the monitoring ICs110, which can reduce power supplied from the high-voltage battery 200to the monitoring ICs 110. This can reduce variations in the capacity ofeach of the cells 201 of the high-voltage battery 200 caused by powersupply to the monitoring ICs 110 and allow the high-voltage battery 200to deliver its inherent performance.

The presence of a high-voltage driven section and a low-voltage drivensection within each of the monitoring ICs 110 allows not only thelow-voltage battery 300, but also the high-voltage battery 200 to beused as a power supply to the monitoring IC 110 in the first-class modesof operation. This eliminates the need for boosting the voltage of thelow-voltage battery 300, thereby reducing power losses caused byboosting the voltage of the low-voltage battery 300.

Circuits driven by the high-voltage battery 200 may be configured toconsume a small amount of current, which can reduce heat generation inthe monitoring ICs 110 and downsize the monitoring ICs 110. This canalso reduce the consumption of power from the high-voltage battery 200.

The presence of a voltage translator circuit and a diode within themonitoring IC 110 may respectively lead to power consumption caused byoperation of the voltage translator circuit and leak current in thediode. As such, upon selection of a source of power, power supplied froman unselected source of power is blocked by using the first switch 111and the second switch 112, which can save power.

Even with the second switch 112 kept open, the presence of therectification circuit at the output end of the insulating power supplyblock 120 may lead to power consumption caused by driving thecentralized transformer 122. Such power consumption in the rectificationcircuit may be suppressed by blocking power supply from the low-voltagebattery 300 to the insulating power supply block 120 via the transistor130 and thereby stopping driving the centralized transformer 122.

Use of the centralized transformer 122 as a low-voltage power supplycircuit allows the single power supply IC 121 to control the insulatingpower supply block 120, which leads to reduced manufacturing costs.

Use of the centralized transformer 122 as a low-voltage power supplycircuit allows parallel power supply to the plurality of monitoring ICs110. This can reduce a wasteful wait time caused by delay in powersupply to some of the monitoring ICs 110 upon initiation of the powersupply to the monitoring ICs 110. In addition, terminating the powersupply to the insulating power supply block 120 enables terminating thepower supply to the plurality of monitoring ICs 110 simultaneously. Thiscan eliminate the need for transmission of a termination signal to eachof the plurality of the monitoring ICs 110, which can reduce theprocessing burden on the higher-level ECU.

The low-voltage battery 300 is electrically connected to the insulatingpower supply block 120 through the transistor 130. Hence control signalsdon't have to be transmitted to the power supply IC 121 upon initiationand termination of the power supply from the insulating power supplyblock 120 to the monitoring ICs 110, which simplifies the process.

MODIFICATIONS

In the embodiment set forth above, the second switches 112 and thetransistor 130 are both provided in the battery monitoring apparatus100. Alternatively, only either one of the second switches 112 and thetransistor 130 may be provided in the battery monitoring apparatus 100.

In the embodiment set forth above, the transistor 130 is provided in thebattery monitoring apparatus 100, where the insulating power supplyblock 120 is disconnected from the low-voltage battery 300 by openingthe transistor 130. Alternatively, the transistor 130 may be removed,where driving the insulating power supply block 120 may be terminated bytransmitting a termination signal from the higher-level ECU to the powersupply IC 121.

In the embodiment set forth above, the self-diagnostic mode of operationis included in the first-class modes of operation, and the equalizationmode of operation and the sleep mode of operation are included in thesecond-class modes of operation. Alternatively, another mode ofoperation may be included in the first- or second-class modes ofoperation depending on its power consumption.

In the embodiment set forth above, the centralized transformer 122 isprovided in the single insulating power supply block 120, and power issupplied from the single insulating power supply block 120 to theplurality of monitoring ICs 110. Alternatively, a plurality ofinsulating power supply blocks 120 may be provided, one for each of theplurality of monitoring ICs 110, where power is supplied from each ofthe plurality of insulating power supply blocks 120 to a correspondingone of the plurality of monitoring ICs 110. In such an alternativeembodiment, each of the plurality of insulating power supply blocks 120may include a transformer formed of a pair of primary and secondarycoils 122 a, 122 b.

In the embodiment set forth above, whether to select the first-classmodes of operation or the second-class modes of operation is determineddepending on whether the ignition switch is on or off. Morespecifically, when the ignition switch is on where the batterymonitoring apparatus 100 conducts the self-diagnostic mode control, thefirst-class modes of operation are selected. When the ignition switch isoff where the battery monitoring apparatus 100 is in sleep mode, thesecond-class modes of operation are selected.

As above, whether to select the first-class modes of operation or thesecond-class modes of operation is determined only on the basis ofwhether the ignition switch is on or off, which simplifies the processof determining the modes of operation.

Reference has been made to specified embodiments in describing theinvention. However, additions, deletions substitutions, or othermodifications which would fall within the scope of the invention definedin the claims may be found by those skilled in the art and familiar withthe disclosure of the invention. Any modifications coming within thespirit and scope of the following claims are to be considered part ofthe present invention.

What is claimed is:
 1. A battery monitoring apparatus comprising: aplurality of monitoring integrated circuits (ICs) ICs including at leastone monitoring integrated circuit (IC) that is electrically connected toa high-voltage battery formed of a plurality of cells and configured tomonitor the high-voltage battery in a plurality of modes of operation,the plurality of modes of operation including first-class modes ofoperation, in which the power consumption of the at least one monitoringIC is equal to or greater than a predetermined value, and second-classmodes of operation, in which the power consumption of the at least onemonitoring IC is less than the predetermined value; and a low-voltagepower supply circuit configured to deliver power that is lower involtage than the power of the high-voltage battery from a low-voltagebattery to the at least one monitoring IC, the low-voltage battery beingseparate from the high-voltage battery, wherein a power supply to the atleast one monitoring IC is selected from a group of the high-voltagebattery and the low-voltage power supply circuit depending on the modeof operation of the at least one monitoring IC, in the first-class modesof operation, the at least one monitoring IC is powered by thelow-voltage power supply circuit, in the second-class modes ofoperation, the at least one monitoring IC is powered only by thehigh-voltage battery, the second-class modes of operation include asleep mode of operation, in which none of various control functions areexecuted, and an equalization mode of operation, in which the pluralityof cells forming the high-voltage battery are equalized in capacity, thelow-voltage power supply circuit comprises an insulating portion, andpower originating from the low-voltage battery is delivered to the atleast one monitoring IC through the insulating portion of thelow-voltage power supply circuit, and the low-voltage power supplycircuit comprises a centralized transformer configured to deliver powerto the plurality of monitoring ICs.
 2. A battery monitoring apparatuscomprising: at least one monitoring integrated circuit (IC) that iselectrically connected to a high-voltage battery formed of a pluralityof cells and configured to monitor the high-voltage battery in aplurality of modes of operation, the plurality of modes of operationincluding first-class modes of operation, in which the power consumptionof the at least one monitoring IC is equal to or greater than apredetermined value, and second-class modes of operation, in which thepower consumption of the at least one monitoring IC is less than thepredetermined value; and a low-voltage power supply circuit configuredto deliver power that is lower in voltage than the power of thehigh-voltage battery from a low-voltage battery to the at least onemonitoring IC, the low-voltage battery being separate from thehigh-voltage battery, wherein a power supply to the at least onemonitoring IC is selected from a group of the high-voltage battery andthe low-voltage power supply circuit depending on the mode of operationof the at least one monitoring IC, in the first-class modes ofoperation, the at least one monitoring IC is powered by the low-voltagepower supply circuit, in the second-class modes of operation, the atleast one monitoring IC is powered only by the high-voltage battery, thelow-voltage power supply circuit comprises an insulating portion, andpower originating from the low-voltage battery is delivered to the atleast one monitoring IC through the insulating portion of thelow-voltage power supply circuit, the at least one monitoring ICcomprises a plurality of monitoring ICs, and the low-voltage powersupply circuit comprises a centralized transformer configured to deliverpower to the plurality of monitoring ICs.
 3. The apparatus of claim 2,wherein, in the first-class modes of operation, the plurality ofmonitoring ICs are further powered by the high-voltage battery.
 4. Theapparatus of claim 2, wherein selection of the power supply isimplemented by turning on and off at least one switch.
 5. The apparatusof claim 2, wherein the low-voltage power supply circuit comprises apower supply integrated circuit (IC) configured to control power supplyfrom the low-voltage battery to the plurality of monitoring ICs, andwhen the power from the low-voltage power supply circuit to theplurality of monitoring ICs is cut, driving the power supply IC isterminated.
 6. The apparatus of claim 5, wherein the low-voltage batteryand the low-voltage power supply circuit are electrically connected toeach other through an external switching element.
 7. The apparatus ofclaim 2, wherein the apparatus is mounted in a vehicle including anignition switch, and the mode of operation in which the plurality ofmonitoring ICs operate is selected from the plurality of modes ofoperation depending on whether the ignition switch is on or off.
 8. Theapparatus of claim 7, wherein when the ignition switch is off, theplurality of monitoring ICs are powered only by the high-voltagebattery.
 9. The apparatus of claim 7, wherein when the ignition switchis on, the plurality of monitoring ICs are powered by the low-voltagepower supply circuit.
 10. The apparatus of claim 9, wherein when theignition switch is on, the plurality of monitoring ICs are furtherpowered by the high-voltage battery.